Cytogenetic Investigation of Infertile Patients in Hungary: A 10-Year Retrospective Study

Clinical validation of an abbreviated karyotype analysis protocol for fertility evaluation

Conventional G-banded karyotype is an essential tool for detecting chromosomal variants in patients undergoing fertility evaluation. In Australia, 15 cells are traditionally analysed or counted, to enhance detection of mosaic chromosomal variants. However, this protocol is not backed by clinical evidence. This study aims to assess the test performance of an abbreviated 5-cell karyotype analysis protocol in adult patients undergoing fertility evaluation. A retrospective review of 53,293 blood karyotype tests, performed between 2019 and 2023, was conducted on a patient cohort primarily referred by reproductive endocrinology specialists. There were 513 variants reported in this cohort. Low level mosaic variants, where the variant was observed in less than 40% of cells, were reported in 13 cases, or one in 4,100 patients. Due to reduced sensitivity for low level mosaic variants, a 5-cell protocol is estimated to have a test sensitivity of 97.3% and a negative predictive value of 99.97%. A decision-making flowchart is proposed and we show that additional chromosome analysis and/or counts would be triggered in fewer than one in 10 cases using a 5-cell protocol, whilst remaining appropriate for detecting clinically significant mosaicism. A 5-cell karyotype analysis protocol therefore maintains analytical and clinical validity in adult patients undergoing fertility-related blood karyotyping. Future research is recommended to validate these findings across laboratories and to explore their application to other clinical contexts.

Genomic aspects in reproductive medicine

Infertility is a complex disease characterized by extreme genetic heterogeneity, compounded by various environmental factors. While there are exceptions, individual genetic and genomic variations related to infertility are typically rare, often family-specific, and may serve as susceptibility factors rather than direct causes of the disease. Consequently, identifying the cause of infertility and developing prevention and treatment strategies based on these factors remain challenging tasks, even in the modern genomic era. In this review, we first examine the genetic and genomic variations associated with infertility, and subsequently summarize the concepts and methods of preimplantation genetic testing in light of advances in genome analysis technology.

Evaluation of chromosomal abnormalities in the postnatal cohort: A single-center study on 14,242 patients

BACKGROUND AND AIM

Chromosomal analysis is a laboratory technique used to examine the chromosomes of an individual, offering insights into chromosome numbers, structures, and arrangements to diagnose and comprehend genetic diseases. This retrospective study provides a comprehensive understanding of the distribution by indications in a large cohort of 14,242 patients and the frequency of chromosomal abnormalities in different clinical populations.

METHOD

The study examined various indications for karyotype evaluation, with recurrent pregnancy loss being the most common indication, followed by intellectual disability, dysmorphic features, congenital anomalies, and developmental delay.

RESULTS

The overall chromosomal abnormality rate was found to be 5.4%, with numerical abnormalities accounting for the majority of cases (61.7%). Trisomies, particularly trisomy 21, were the most frequent numerical abnormalities. In terms of structural abnormalities, inversions and translocations were the most commonly identified. The rates of chromosomal anomalies varied in specific indications such as amenorrhea, disorders of sex development, and Turner syndrome. The study also highlighted significant differences between males and females in the presence of chromosomal abnormalities across certain indications. Males exhibited a higher incidence of chromosomal abnormalities in cases of Down syndrome and infertility, whereas females showed higher abnormalities in terms of recurrent pregnancy loss.

CONCLUSION

While this study provides valuable insights into the frequency and distribution of chromosomal abnormalities, it has limitations, including its retrospective design and reliance on data from a single medical genetics department. Nevertheless, the findings emphasize the importance of karyotype analysis in diagnosing chromosomal disorders and providing appropriate management, while also pointing to potential gender-related variations in chromosomal abnormalities that warrant further investigation.